Guidelines to Implement Monitoring and Remote Control System in an Urban Distribution Grid

Abstract: The distribution grid has traditionally been a robust design where the lines are protected by the primary substation. Constant access to electricity is important for our society, and a power interruption can have large consequences. Power interruptions also reduce the revenue cap, i.e., how much the utility can charge its customers. Additionally, in the newest regulation from the Swedish Energy Markets Inspectorate, communication and remote control equipment obtained a regulatory value, and the revenue cap increases if that kind of equipment is installed in the grid. Therefore, it has been more attractive for the utility to invest in monitoring and remote control equipment in their distribution grids. In a customer-dense area with high interruption costs, the main question is not if monitoring and remote control should be installed. The question is how to do it and where to start. This thesis aims to give guidelines for implementing monitoring and remote control equipment in an urban distribution grid. The structure of a distribution grid, the system grounding, and the basic principles of fault identification, isolation, and restoration of the system are described. A simulation model for a single cable fault is developed. Cable fault is the most common failure in an underground cable grid. Three different levels of automation are used in the model: level 0 -no communication at all; level 1 -monitoring of the station in SCADA/DMS where at least information from fault indicators is sent; level 2 -monitoring and remote control, the switches can be operated from a SCADA/DMS system. In the simulation, two different datasets are used: reference feeder and real data feeders. The results are evaluated feeder by feeder and in a small grid where several feeders were combined. In total, as long as at least 60-75 % of the secondary substations in the feeder have level 1 or level 2 equipment, the interruption cost and SAIDI decrease by at least 70 %. The result also shows that the strategy to reduce interruption costs is different from the strategy to reduce SAIDI. The network structure is an important factor, and just introducing communication and monitoring and remote control systems will not automatically become a quality boost for the utility company. To implement the technology, broad knowledge and understanding about all parts in the distribution grid is necessary. This includes knowledge about the primary and secondary equipment, the communication, and the limitation of the different parts.